Credit is given for each family of which you raise a pet from level 9 to level 10. This means first buying a caged level 9 pet, or capturing a level 9 wild pet (which will retain its level after capture) is the most efficient method for getting this achievement.

Before this first tier achievement is completed, the second tier achievement All Pets Allowed already starts tracking progress, so no credit towards that achievement is missed. This means it most effective to first level a team to 25, and then powerlevel the pets still required for this achievement to 10.

Comment by brionl

For people who want to get a head start on this/cheese the achievement, I've compiled a list of pre-Mists pets of each family that will be rare. Assuming the list posted on the WoW beta forums doesn't have any removed. I'll mostly try to use pets that are non-TCG/Promotional.

If there are any more suggestions for pets that are currently in the game, not-TCG, not-Promotional, not-Pet Store feel free to add them.

Comment by brionl

You have to raise a pet to level 10. Capturing a pet 10 or higher does not count.Capturing a level 9 (or lower) pet, and raising it to level 10 does work though.

Comment by bqiyue2

If you level one or more pets to lv.25 before getting this achievement, your progress on the next one will be kept but hidden. Once you earned this achievement, criteria that you already fulfilled will be displayed on the next one.

Comment by Niaw

If you already have one or two level 25 pets, then levelling more of the families you're missing can be easy by fighting high level opponents. You only need for your low level to survive one round, then put it away and kill with a high level. If you use both high levels, then deliberately kill one off so it doesn't subtract from the final exp. With this method you can usually get over three levels for your pet in the first battle (level 1-4), then two levels for the next couple of battles. By then you're almost there. It's over so quickly it doesn't matter too much what level the pet started as, as long as it's under level 9.

But if you don't have high levels and you're after the fastest possible solution, then you probably want to start with pets as close to level 9 as possible. Level 9 pets are found mostly in the Southern Barrens and the Cape of Stranglethorn, but not all families are represented there. In fact not all families have capturable battle pets under level 10. And, of course, if you want to level rares, then it may be faster to level lower level ones that you already have than finding new ones already at level 9.

Anyway, as far as I can tell, the ones that have capturable members at level 9 are:

As far as I can tell, there are no capturable battle pets in the level 2-9 range for the Dragonkin, Humanoids or Magic families. You'll have to level them from 1. I'm very happy to be corrected if I'm wrong though :)

Comment by Sasmina

I found that the fastest way to do this is by battling pets much higher level than your own pet.

What I did was that I got my good old lvl 25 pets, made a team with 2 x lvl 25 pets, and then the lvl 1 pet that you wanted to lvl. Start off by killing a few lvl 1 pets to get to level 3 so you get your 2nd spell. Then head off to Pandaria and battle lvl 25 mobs. Get your lvl 25 pets to damage them down to an amount of health where your lvl 3 pet can oneshot it, then change to your lvl 3 pet and pray that it won't miss.

If your lvl 3 pet kills one of the lvl 25 enemy pets it will instantly get a level because of the massive amount of exp gained :)

Anyway, that is how I would prefer to do it :)

- Sas

Comment by Zurgan

leveled a beetle from 9-10 but it didnt count

Comment by dragonkilla08

Leveling your low-level pets with two level 25s as backup is a great idea, however be careful using this method. If your pet just jumps over level 9 and goes straight from 8 to 10 or similar from 9 to 11, it will not count towards this achievement.

Found that out the hard way myself while leveling up the couple types I needed.

Comment by Burnay

A good way earn this achieve is to follow the guide by "jjanchan" at the top of the comments section on the Thundering Pandaren Spirit page. If you have a lvl one carry pet with his strategy it will immediately be lvl 10 upon victory.

Since you can fight him once a day you can get another pet family raised to lvl 10 once a day.

Comment by Baluki

This seems to be broken, as of 5.3 (at least for some people). I've got numerous pets over lvl. 20 at this point, and not one of the steps is completed for me, which is impossible.